Signal processing apparatus

ABSTRACT

1. Apparatus for processing radar signals and the like, comprising WIDEBAND SIGNAL RECEIVING AND TRANSMITTING ANTENNA MEANS; CIRCULATOR MEANS HAVING A FIRST TERMINAL CONNECTED WITH SAID ANTENNA MEANS, SAID CIRCULATOR MEANS INCLUDING ALSO SECOND AND THIRD TERMINALS; A FIRST TUNED MICROWAVE MIXER SET INCLUDING A FIRST DIRECTIONAL FILTER, A PLURALITY OF FIRST DIRECTIONAL FILTER MIXER UNITS EACH TUNED TO A DIFFERENT DISCRETE FREQUENCY BAND, AND FIRST MANIFOLD MEANS CONNECTING SAID FIRST MIXER UNITS WITH SAID FIRST DIRECTIONAL FILTER; A SECOND TUNED MICROWAVE MIXER SET INCLUDING A SECOND DIRECTIONAL FILTER, A PLURALITY OF SECOND DIRECTIONAL FILTER MIXER UNITS CORRESPONDING IN NUMBER WITH SAID FIRST MIXER UNITS AND BEING TUNED TO THE CORRESPONDING FREQUENCY BANDS THEREOF, RESPECTIVELY, AND SECOND MANIFOLD MEANS CONNECTING SAID SECOND MIXER UNITS WITH SAID SECOND DIRECTIONAL FILTER; FIRST COMMON CONDUCTOR MEANS CONNECTING THE MIXTURE UNITS OF THE FIRST SET WITH THE SECOND TERMINAL OF SAID CIRCULATOR MEANS, SAID FIRST CONDUCTOR MEANS CONTAINING SERIES-CONNECTED SERIESCONNECTED SWITCH; SECOND COMMON CONDUCTOR MEANS CONNECTING THE MIXTURE UNITS OF THE SECOND SET WITH THE THIRD TERMINAL OF SAID CIRCULATOR MEANS; LOCAL OSCILLATOR SIGNAL GENERATOR MEANS; FIRST GATE MEANS CONNECTING SAID SIGNAL GENERATOR MEANS WITH ALL OF THE MIXER UNITS OF SAID FIRST SET; A PLURALITY OF SECOND GATE MEANS CONNECTING SAID SIGNAL GENERATOR MEANS WITH THE MIXTURE UNITS OF SAID SECOND SET, RESPECTIVELY; AND SIGNAL PROCESSING MEANS HAVING INPUT AND OUTPUT TERMINALS CONNECTED WITH THE DIRECTIONAL FILTERS OF SAID FIRST AND SECOND SETS, RESPECTIVELY, FOR CONTROLLING THE OPERATION OF SAID SWITCH AND OF SAID FIRST AND SECOND GATING MEANS AS A FUNCTION OF THE INHERENT CHARACTERISTICS OF SIGNALS RECEIVED BY SAID ANTENNA MEANS AND FOR RETURNING TO THE DIRECTIONAL FILTER MEANS OF SAID SECOND SET A MODIFIED FACSIMILE SIGNAL.

United States Patent 1 Lawsine 1March 13, 1973 l l SIGNAL PROCESSINGAPPARATUS [76] Inventor: Leo Lawsine, 807-South Barton Street,Arlington, Va.

[22] Filed: Dec. 29, 1964 [211 Appl. No.: 421,826

[52] US. CL. ..343/18 E [51] Int. Cl. ..II04k 3/00 [58] Field of Search..343/l8,18 E, 6.5, 6.8

Primary EiaininerSamuel Feinberg Assistant Examiner-G. E. MontoneAttorney-Lawrence E. Laubscher EXEMPLARY CLAIM 1. Apparatus forprocessing radar signals and the like,

' comprising second directional filter, a plurality of seconddirectional filter mixer units corresponding in number with said firstmixer units and being tuned tothe corresponding frequency bands thereof,respectively, and second manifold means connecting said second mixerunits with said second directional filter;

first common conductor means connecting the mixture units of the firstset with the second terminal of said circulator means, said firstconductor means containing series-connected series-connected switch;

second common conductor means connecting the mixture units of the secondset with the third terminal of said circulator means;

local oscillator signal generator means;

first gate means connecting said signal generator means with all of themixer units of said first set;

a plurality of second gate means connecting said signal generator meanswith the mixture units of said second set, respectively;

and signal processing means having input and output terminals connectedwith the directional filters of said first and second sets,respectively, for controlling the operation of said switch and of saidfirst and second gating means as a function of the inherentcharacteristics of signals received by said antenna means and forreturning to the directional filter means of said second set a modifiedfacsimile signal.

4 Claims, 2 Drawing Figures ioossonke 2E295? Am FREQ wucno bALANQEDamgr) VARIABLE IF UNIT "g WAVE MIXER DELAI DELI-N AMP -2 AMP 2.. 60 LINEL"\ H6 n 4:] c; I I a 2-9 q O Cg 5 IAGC. 4.|-7.|qc. 22 f 5 DELAYED lCROSSED MICROWAVE 7 HYBQID Fl 5'53 mom END ED JLNCTION 2'4qc MIXER once1 DELAYED I4 41- 7.1 COMPUTER DOPPLER comic-rim l DUPLEXER 16 MEANS4.l-'ll qc i 2| d' qc omce. TUNED gag ihzqg DELAYED MIXER LQ q i l lOl ino I3 osc.

GATES 1 K) L R 9 a ma? 0 L ZSJMICRO ATTEN MICRO BALANCED 1 AMP AM? MIXED7 9% I 2 DELAVED DELAYED DELAYED SIGNAL PROCESSING APPARATUS operationalcapabilities. Many of the known systems include equipment that is largeand massive, thus reducing the useable interior capacity and flightrange of the spacecraft. Furthermore, certain types of complexcountermeasure systems require manual operation and/or control by highlytrained technical personnel, further increasing the size of the flightcrew and the attendant problems of aircraft design.

The primary object of the present invention is to provide an improvedelectronic countermeasure system that is reliable and flexible inoperation, that is relatively inexpensive relative to the knownsysterns, and that lends itself to semi-automatic or fully-automaticoperation.

A more specific object of the invention is to provide a countermeasuresystem for aircraft, seaborne and ground installations that isinstrumented to perform, in real time, all the important deceptionrepeater jamming operations. The system is operable to repeat pulse orcontinuous wave signals against anywhere from one to 100 hostile radarsoperating in either the search or track-mode. The system performs alsoagainst radars provided with electronic counter-countermeasure means,such as frequency diversity, frequency jumping, and random, staggered,jittered or coded pulse repetition rate frequencies. The presentinvention, which makes use of programmed computer control means inresponse to the specific characteristics of the hostile radar signal, isoperable to repeat either earlier or later in time the true target echo,whereby the repeated echo appears at a shorter or longer range on aradar display (or as recorded on a data processor). Furthermore, thepresent system includes doppler correction means that supply a dopplerfrequency correction to compensate for different simulated vehiclespeeds in correlation with the repeated echo.

The system of the present invention, which repeats a signal based on thecharacteristics of the received signal, may be programmed to change thetime of retransmission, the time base (i.e., compress or expand the timeframe) or to communicate between a number of systems. In the electroniccountermeasure mode of operation, all of the operational features arecorrelated in terms of time, frequency and phase. The system is alsoapplicable foruse in the communication mode as a link in a communicationsatellite network, for example.

The invention is characterized by the provision of m-ulti-spectralcomponent mixing program means affording precise control of time,frequency and phase. Use is made of novel microwave front end means incombination with special programmed computer control means. i

With regard to a typical tactical mission, as the vehicle with theelectronic countermeasure deception jamming system approaches thehostile radar, an analysis is continuously made of all program inputs.Such information is partially derived from ancillary equipment in thevehicle, and partly from intelligence supplied prior to the mission. Thedate from these two sources are associated with real and non-real time.Included are such parameters as pulse repetition frequency, altitude,angle (azimuth and elevation), pulse duration, scan rate, target crosssection, radar power, slant range, relative strength of main and sidelobes, speed of the vehicle, and the like. The operator of the vehicleselects a predetermined program (on a tape, for example) in accordancewith the prearranged tactics and new factors as they develop.

When the vehicle is within range of the hostile radar, the systemrepeats during real time, the radar signals in both the search and trackmodes. On each radar display, the false echo signal produced by thesystem appears at least as strong as the expected target echo (since thesystem operates as a one-way transmitter as distinguished from thetwo-way reflection radar system). If the false echo represents the radarsignal repeated earlier, it appears at a short range. Furthermore, itcan be made to move faster than the target echo i.e., it will simulate ahigher speed by closing the range faster. At the same time, the dopplerfrequency shift (corresponding to the higher speed) is also generated.This doppler shift may be achieved at speeds ranging from a few milesper hour to speeds on the order of Mach 5 or greater.

Since the signal from the vehicle may be programmed to come down asidelobe of the radar beam, the repeated signal will also be false inangle (for both the search and track modes). Even sophisticatedmonopulse tracking radars could be deceived into tracking with theirside lobes.

The system is capable of automatically repeating pulse or continuouswave signals against or more radars, depending on computer capacity,duty cycle, signal characteristics, electronic countermeasure techniquesand tactical requirements. The operational capabilities are achieved byautomatic processing of the spectral components of the radar signal.Such frequency domain operation utilizes unique techniques to controlfrequency and pulse transmission instantly and automatically. To thisend, the frequency components are filled in or reinserted as directed bythe computer program.

Other objects and advantages of the invention will become apparent froma study of the following specification when considered in conjunctionwith the accompanying drawing, in which:

FIGS. 1 and 2 are simplified and detailed illustrations, respectively,in block diagram form, of the wide band electronic countermeasuredeception repeater jammer system of the present invention.

Referring first to FIG. 1, the wide band antenna 1 is of the equiangular(or logarithmic) spiral type broadbanded over 2 or more octaves. Suchantennas are particularly suitable for high speed airborne and spacevehicles. The antenna phase centers are frequency scanned by frequencyscanner 2 at a programmed rate (e.g., 20 or 30 megacycles) duringreception and are directed to a specific location during transmission.The frequency scanner is controlled by a programmed computer 3 toperform several functions as will be described in greater detail below.The computer, which may be of any suitable type (for example, theGeneral Electric A-236 Real Time Computer including such units as aconventional clock, counter, ring counter, memory, address matrix,address scanner, subtractor and gate former circuits) is operable toprovide the unique results of the present invention. By means of theantenna scanning means, an effective area, up to 180 solid angle, forexample, may be scanned from the underside of an airplane wing duringreception, and steered to a selected location within nanoseconds duringtransmission. For any radar mode of operation (i.e., search or track)the system of the present invention will receive, process and repeatcontinuous wave or radiofrequency pulses in the range covering themicrowave bands generally used by radars. In describing systemoperation, a typical signal range from 2-9 gigacycles has been selected.

During reception (i.e., the scanning period) the radar signal passesthrough a crossed field amplifier 4 which serves as a passive low lossdevice (0.5 decibels) in the receive direction. The signal enters themicrowave front end 5 where it is separated by duplexer 6 into two ormore paths depending on the desired signal bands. In the illustratedembodiment, the signal is divided into two bands (specifically, 2-4 and4-9 gigacycles). Signals falling in the lower and upper bands are fed tothe tuned microwave mixer sets Tand 8, respectively, depending on thesignal frequency. Since the operation of the mixers 7 and 8 isidentical, in the following description only the processing of thesignals in the 2-4 gigacycle range will be described.

Local oscillator 9, which is also controlled by the computer 3,generates signals in the 1-2 gigacycle range that are applied to thetuned mixers 7 and 8 via the IO-gate computer-controlled oscillator gatemeans 10. The local oscillator 9 may be a carcinotron operating as avoltage tuned backward wave oscillator, or a travelling wave tube withregeneration. The local oscillator frequencies (in the 1-2 gigacyclerange) may be obtained by modulating the carcinotron sole with whiteGaussian noise at a high frequency rate, for example, in the range 10 to30 megacycles. This technique effectively fills in frequency holes thatmight result from the use of Gaussian noise alone. The oscillatorfrequency spectrum then contains all frequencies over the band 1-2gigacycles. [n the illustrated embodiment, the local oscillator gatemeans comprise diode switches controlled by the computer 3.

The output signal from the tuned microwave mixer set 7, which representsthe sum and difference frequency components, is filtered through unit 7(which passes spectral components in the range 4-7 gigacycles) and isapplied to the microwave amplifier 11. At the input to amplifier 11.(which may be a traveling wave tube), the signal level is approximately90 decibels. For a nominal gain of 25 decibels, the amplifier output ison the order of 65 decibels. Preferably the amplifier 11 is providedwith instantaneous automatic gain control for suppressing ring-aroundaction.

The output from the amplifier is applied to the balanced mixer 12 formixing with a signal that is supplied by the computer-controlled localoscillator 13 via hybrid junction 14 as programmed by the computer. Thelocal oscillator frequency band covers the range of 4.1-7.1 gigacycles.The output signal from mixer 12, is amplified by the broadbandintermediate frequency amplifier 15 at 100 i 60 megacycle bandwidth.Selection of the IF bandwidth is based on the smallest anticipated timedelay inherent in the system (on the order of 0.05 to 0.1 microseconds).The local oscillators 9 and 13 may time share a single local oscillatorcomponent controlled by computer 3.

The derived 100 t 60 megacycle broadband signal is fed through the fixedand variable delay lines 16 and 17, and the delayed signal is amplifiedby the intermediate frequency amplifier l8 and is applied to one inputof the balanced mixer 19. As indicated by the broken line 20, thevariable delay line 17 is associated with a doppler correcting means 21that is conventional in the art and includes a variable speed means,servomotor amplifier means, a motor, a generator, a differentialgenerator and an attenuator. While the amplifier 15, the fixed andvariable delay means 16 and 17, the amplifier 18, and the doppler means21 constitute conventional matching components, the delay lines(generally quartz) may be modified in accordance with the-anticipatedpulse repetition frequency, the simulated vehicle speed (correlated withthe doppler frequency shift of the repeated pulse) and the tacticalconsiderations envisioned. In this respect, the range of correctionsapplicable on doppler frequency shifts will vary from 0.1 to 15microseconds or higher to cover a range of speeds from miles per hour toMach 13 or higher. A typical length of the quartz line (for a 500microsecond delay)is equivalent to about 40 miles in range. Theoperation and structure of the doppler correcting means will bedescribed in greater detail below. Pulse repetition information is alsosupplied by the IF amplifier 15 to the computer 3 via conductor 22. Theprogrammed computer automatically utilizes the spacing betweenconsecutive pulses for timing and delay purposes. Consequently, areceived signal with random, jittered, staggered or coded pulserepetition frequency will be processed in such a manner that therepeated signal will appear as a valid target return to the hostileradar.

1n the balanced mixer 19, the i 60 megacycle signal is mixed with the4.1 to 7.1 gigacycle signal supplied by oscillator 13 via hybridjunction 14 as controlled by the computer program. The reconvertedoutput of the mixer 19, having a typical level of 65 decibels, is now abroadband delayed signal. This signal is amplified by microwaveamplifier 23 (which comprises, for example, a traveling wave tube) andappears as an approximately 40 decibel signal level that is attenuatedby attenuator 24 which supplies a standard level to microwave amplifier25. This latter amplifier brings the output signal to a level suitablefor processing by the microwave front end means 5. Instantaneousautomatic gain control may be supplied to microwave amplifier 23 toprevent ring around effects.

The delayed signal that is applied to the mixer set 8 of the front end 5is filtered to supply spectral components in the 4-7 gigacycle rangethat are mixed with the l-2 gigacycle localv oscillator signals suppliedvia the computer controlled gates 10.

The resultant signal, which represents a reconstituted facsimile of theoriginal radar signal that is delayed in time and corrected for apredetermined doppler shift, is then passed through duplexer 6 to thecrossed-field amplifier 4 which provides a nominal power gain ofapproximately 20 decibels. As directed by the computer program, thesignal is amplified by the amplifier 4 and is repeated from antenna 1 toa selected location or radar site.

I Referring now to FIG. 2, the duplexer 6 of the microwave front endincludes a filter diplexer 40 that separates the incoming signal intotwo or more paths (specifically, those including the bands 2-4gigacyclcs and'4-9 gigacycles'in the' described embodiment). The

operation of each band path is substantially identical. The duplexer 6includes circulators 41 and 42 associated with the respective bands. The2-4 gigacycle range signals from the filter diplexer 40 are applied, viacirculator 41 and nanosecond switch 43, to the input directional filtermanifold 44 having a termination 45. The filter manifold coveys thesignal to a plurality of directional filter mixers 46-49 which serve astuning elements and mixers to separate the signal into discreteoverlapping narrow band channels. If needed, ancillary equipment may beprovided to afford adju'stability as desired. Similarly the 4-9gigacycle range signals from filter diplexer 40 are applied, viacirculator 42 and nanosecond switch 53, to the input directional filtermanifold 54 having a termination 55. The switching operations ofswitches 43 and 53 during both the reception and repeating periods arecontrolled by computer 3. During reception switches 43 and 53 and thediode switch associated with the output 110 of oscillator gate 10 areclosed while the diode switches associated with gates 101-109 are open.During repeating, switches 43 and 53 and gate switch 110 are open, whilegate switches 101-109 are closed as determined by the computer program.The switches 43 and 53 provide nanosecond operation.

Thus, in the reception period, for a signal in the 2-4 gigacycle range,the local oscillator signal band (1-2 gigacycles) is fed to all tunedmixer elements in such a manner that mixer outputs are produced only inthose elements that are tuned to the radar input signal. The mixeroutput signal, which consists of the sum and difference products, isrouted via waveguide or stripline channels (with suitable interfacingjoints, if desired) to the output directional filter manifold 60having'a termination 61. The signal passes through directional filter 62which filters out spectral components in the range of 4-7 gigacycles.Filter 62 is designed with proper bandpass or band rejection skirts tochannel out only 4-7 gigacycle components. The spectral output is nowpassed through filter diplexer 63 to microwave amplifier 11.

in a similar manner, a signal in the 4-9 gigacylce range is processedfrom circulator 42 via switch 53 to the input directional filtermanifold 54. The signal is applied to one or more of the directionalfilter mixers 66, 67, 68, 69 and 70 (in accordance with signalfrequency) and is mixed with the 1-2 gigacycle local oscillator signalgated via diode switch gate 110. The resulting mixer output signal isthen routed via waveguide or stripline channels to the outputdirectional filter manifold 72 having a termination 73.

' The signal is filtered through directional filter 74 which passes the4-7 gigacycle spectrum components to microwave amplifier 1 1 viadiplexer 63.

The tuning ranges of the directional filter-mixers are as follows:

During During reception transmission filter-mixer 46 134 2.0-2.5gigacycle filter-mixer 47 135 2.5-3.0 gigacycle filter-mixer 48 1363.0-3.5 gigacycle filter-mixer 49 B7 3.5-4.0 gigacycle filter-mixer 66138 4.0-5.0 gigacycle filter-mixer 67 139 5.0-6.0 gigacycle filter-mixer68 140 6.0-7.0 gigacycle filter-mixer 69 l4l 7.0-8.0 gigacyclefilter-mixer 70 142 8.0-9.0 gigacycle Thus the signal supplied tomicrowave amplifier 11 contains 4-7 gigacycle spectral componentsrepresentative of the radar signal in the range 2-9 gigacycles. As notedbefore, it is amplified by amplifier l1 and is converted in balancedmixer 12 with the local oscillator 4.1-7.1 gigacycle signal supplied viahybrid junction 14 as programmed by computer 3. The resulting signal isamplified by intermediate frequency amplifier 15 with a passband of 100i 60 megacycles, and is fed to computer 3 and fixed delay line 16.

The computer 3 performs three distinct functions. First, it stores thepulse repetition frequency information in the memory storage section.Secondly, it controls the timing of all system functions, such asstarting, stopping and switching. Finally, it processes pulse repetitionfrequency information (whether regular or irregular). The storage andtiming functions are accomplished in a conventional manner and need notbe described in detail. For the processing of the pulse repetition,rate-frequency, however, novel means are provided for utilizing thedifference in time between consecutive pulses to determine a gate widthwhich will cause certain pulses to be repeated at such a time that thehostile radar is deceived (that is to cause the radar to accept thepulse as one of its own reflected signals). Thus, the computer clocktimes all units of the computer at a given rate (for example, at a lmegacycle rate). Thus, the signal supplied to computer 3 from theintermediate frequency amplifier 15 via conductor 22 starts a counter 91which is gated by ring counter 92 operating at a nominal rate of 2megacycles. The counter 91 resets ring counter 92 which shifts from gate1 to gate 2 and so forth to gate n. The outputs on lines 1, 2 n(corresponding to the gates) are committed to the memory 93. Words t,...t,, are called from memory 93 by the address matrix 94 when actuated bythe address scanner 95. The address scanner is essentially an additionunit which gates the lines 1, 2 n from the memory so that words 1,, t,t, will be allowed through subtractor 96. The subtractor puts outdifferences A At, At, between consecutive pulse intervals into gateformer 97 which forms l more pulse than the word. Thus a zero timedifference produces 1 pulse, l unit time difference produces 2 pulses, 2units produces 3 pulses, and so forth. These pulse outputs from the gateformer modulate the crossed field amplifier 4 which repeats theradiofrequency signal in these several pulses so that the hostile radarselects only its own radiofrequency pulse signal and throws out all theother pulses. In this manner, it is possible to repeat effectivelyagainst radar with irregular pulse repetition rate frequencies, e.g.,staggered, jittered, random, coded signals and the like.

The fixed delay line 16 consists of one or more sections which cover theradar pulse repetition frequency signal range with anticipated pulseintervals. Variable delay line 17 supplies a fine adjustment for thetotal delay and a rate of change of delay to represent the range rate ofthe repeated echo. With respect to this latter function, dopplercorrecting network 21 operatesas follows. The variable speed drive 126is set for the airborne or spaceborne vehicle in which it is. installed.The drive output feeds servo amplifier 121 that drives motor 122. Themotor, which is calibrated in terms of equivalent feet of delay line, ismechanically linked with variable delay line 17, generator 123', anddifferential generator 124. As part of the servo loop, the generatorsmooths out variations in motor speed (whereby the speed is maintainedconstant) such that the rate of change of the variable delay line is atrue equivalent of the input speed information (i.e., the range rate).Differential generator 124 transforms the rate of change of delay lineinto a doppler voltage which is passed to attenuator 125 and then tomicrowave amplifier 23 (specifically, to the helix of a travelling wavetube). This results in a phase change of the delayed radiofrequencysignal that is correlated with the desired speed of the vehicle at alltimes.

The delayed intermediate frequency at 100 i 60 megacycles is mixed inbalanced mixer 19 with the 1.4-7.1 gigacycle local oscillator signalband generated by local oscillator 13 and gated by hybrid junction 14.This reconversion produces delayed spectral components which areattenuated and further amplified in microwave amplifier 23.

The delayed signal is routed via filter dipl exer 127 to directionalfilters 128 and 129 which filter out the 4-7 gigacycle spectralcomponents. This signal appears in input directional filter manifolds130 and 131 having terminations 132 and 133, respectively. The signal isrouted to directional filter mixers 134-137 in the 24 gigacycle path andto directional filter mixers 138-142 in the 4-9 gigacycle path. Then oneor more of the filter-mixer units will be activated with the localoscillator band l-2 gigacycle signal depending on those diode switchgates 101-109 which have been selected by the computer 3. The resultingmixer output from the activated unit now represents a reconstitutedfacsimile of the original radar signal delayed in time and corrected fora predetermined doppler shift. The signal (or signals) are then routed,via the output directional filter manifolds r43 amiss with termination14s and 146, respectively, to circulators 41 and 42 and to filterdiplexer 40. In accordance with the computer program, the delayed anddoppler-corrected signal is amplified in amplifier 4 which may bemodulated with additional pulse gates as previously described. Thesignal is now repeated and beamed via wide band antenna 1 to a selectedlocation or radar site.

It is apparent that the system of the present invention constitutes awide-band, multi-spectral component mixer, duplexer system with computerprogram control of timing, frequency and phase. The system repeatssignals earlier or later with the correct doppler frequency and whenfeasible, will repeat also at a false angle.

The operation may be performed on or more radars, depending on computercapacity and system factors. The system performs satisfactorily even forsophisticated radars using frequency diversity, frequency jumping,monopulse tracking, random, jittered, staggered or coded pulserepetition rate frequency, and so forth.

While in accordance with the provisions of the Patent Statutes, thepreferred form and embodiment of the invention has been illustrated anddescribed, it will be apparent to those skilled in the art that variouschanges and modifications may be made in the apparatus described withoutdeviating from the invention set forth in the following claims.

What is claimed is: i

1. Apparatus for processing radar signals and the like, comprisingwideband signal receiving and transmitting antenna means;

circulator means having a first terminal connected with said antennameans, said circulator means including also second and third terminals;

a first tuned microwave mixer set including a first directional filter,a plurality of first directional filter mixer units each tuned to' adifferent discrete frequency band, and first manifold means connectingsaid first mixer units with said first directional filter; second tunedmicrowave mixer set including a second directional filter, a pluralityof second directional filter mixer units corresponding in number withsaid first mixer units and being tuned to the corresponding frequencybands thereof, respectively, and second manifold means connecting saidsecond mixer units with said second directional filter;

first common conductor means'connecting the mixer units of the first setwith the second terminal of said circulator means, said first conductormeans containing a series-connected switch;

second common conductor means connecting the mixer units of the secondset with the third terminal of said circulator means;

local oscillator signal generator means;

first gate means connecting said signal generator means with all of themixer units of said first set;

a plurality of second gate means connecting said signal generator meanswith the mixer units of said second set, respectively;

and signal processing means having input and output terminals connectedwith the directional filters of said first and second sets,respectively, for controlling the operation of said switch and of saidfirst and second gating means as a function of the inherentcharacteristics of signals received by said antenna means and forreturning to the directional filter means of said second set a modifiedfacsimile signal.

2. Apparatus for processing and repeating radar signals and the like,comprising wideband signal receiving and transmitting antenna means;

first and second circulator means each having a first terminal connectedwith said antenna means, and second and third terminals;

first, second, third and fourth microwave mixer sets each including adirectional filter, a plurality of directional filter mixer units eachtuned to a different discrete frequency band, and manifold meansconnecting saidfilter mixer units with said directional filter, themixer units of said first and second sets being of the same number andhaving corresponding frequency bands, respectively, the mixer units ofsaid third and fourth sets being of the same number and havingcorresponding frequency bands, respectively; first common conductormeans including a first switch connecting the mixer units of the firstset with the second terminal of said first circulator means;

second common conductor means connecting the mixer units of the secondset with the third terminal of said first circulator means;

third conductor means including a second switch connecting the mixerunits of said third mixer set with the second terminal of the secondcirculator means;

fourth conductor means connecting the mixer units of said fourth mixerset with the third terminal of the second'circulator means;

signal processing and modifying means having input and output terminals;

first diplexer means connecting the directional filters of said firstand third mixer sets with the input terminal of said signal processingand modifying means;

second diplexer means connecting the output terminal of said signalprocessing and modifying means with the directional filters of saidsecond and fourth mixer sets;

local oscillator signal generator means;

first gate means connecting said signal generator means with each of themixer units of said first and third mixer sets; and

a plurality of second gate means connecting said signal generator meanswith the mixer units of said second and fourth mixer sets, respectively;

said signal processing and modifying means being operable in accordancewith the inherent characteristic of the signal received by said antennameans to control the operation of said first and second gate means andsaid first and second switches.

3. An electronic countermeasure system for processing theaircraft-seeking signals generated by a hostile radar installation andfor repeating to said radar installation false target echo signals,comprising wideband antenna means operable alternately to receive afirst radar signal and to transmit a processed second radar signal;

microwave front end means connected with said antenna means andincluding first tuned mixer means for placing said first signal within agiven first frequency band;

second mixing means for modifying the output signal of said front endmeans to produce a signal characteristic of, and having a lowerfrequency than, said first radar signal;

delay meansfor delaying said low frequency signal,

said delay means including a variable delay device;

doppler correcting means controlling the operation of said variabledelay device to effect a doppler frequency shift of said low frequencysignal corresponding to a desired repeated echo range rate;

means including third mixer means for placing the delayed and dopplercorrected signal in said first frequency band;

means including said first tuned mixer means for converting the delayedand doppler corrected signal in said first frequency band to theoriginal frequency of said first radar signal and thereby produce saidsecond radar signal;

meansincluding said antenna for transmitting said second radar signaltoward said hostile radar installation; and

computer means responsive to the low frequency signal produced by saidsecond mixing means for controlling the operation of said first mixingmeans.

4. An electronic countermeasure system for processing anaircraft-seeking hostile radar signal within a first frequency band andfor transmitting to said radar installation a processed false targetecho signal having a frequency corresponding with that of the hostileradar signal, comprising wideband antenna means operable alternately toreceive a first radar signal within said first frequency band;

microwave front end means connected with said antenna means for changingthe frequency of said first signal to place the same within a secondfrequency band smaller than the hostile radar signal first frequencyband, said front end means including a plurality of channels eachcontaining a plurality of tuned directional filter mixer means, firstsignal generator means, and gage means connecting said first signalgenerator means with each of said directional filter mixer means,respectively, each of said directional filter mixer means being tuned toa different incremental portion of the hostile radar signal frequencyband;

second mixer means for modifying the output signal of said front endmeans to produce a second signal characteristic of said first radarsignal, said second mixing means including a balanced mixer having afirst input terminal connected with the output of the microwave frontend, a second input terminal, and an output terminal, second signalgenerator means, and hybrid junction means connecting said secondgenerator means with said second input terminal;

fixed and variable delay means connected with the output terminal ofsaid balanced mixer means for delaying said second signal;

doppler adjusting means controlling the operation of said variable delaydevice to effect doppler frequency shift of said second signalcorresponding to a desired repeated echo range rate;

third mixer means including said second signal generator means and saidhybrid junction means for increasing the frequency of the delayed secondsignal;

means including said microwave front end means for converting theincreased-frequency delayed signal to the first frequency band andthereby produce a second signal for controlling the operation of saidprocessed third radar signal; first and second signal generating means,said gate means including said antenna for transmitting said ea Sa d dppler adjusting means and said anprocessed hi d radar Signal toward Saidhostile tenna means as a function of the inherent characradarinstallation; and tetistics of said first Signal programmed computermeans responsive to the

1. Apparatus for processing radar signals and the like, comprisingwideband signal receiving and transmitting antenna means; circulatormeans having a first terminal connected with said antenna means, saidcirculator means including also second and third terminals; a firsttuned microwave mixer set including a first direCtional filter, aplurality of first directional filter mixer units each tuned to adifferent discrete frequency band, and first manifold means connectingsaid first mixer units with said first directional filter; a secondtuned microwave mixer set including a second directional filter, aplurality of second directional filter mixer units corresponding innumber with said first mixer units and being tuned to the correspondingfrequency bands thereof, respectively, and second manifold meansconnecting said second mixer units with said second directional filter;first common conductor means connecting the mixer units of the first setwith the second terminal of said circulator means, said first conductormeans containing a series-connected switch; second common conductormeans connecting the mixer units of the second set with the thirdterminal of said circulator means; local oscillator signal generatormeans; first gate means connecting said signal generator means with allof the mixer units of said first set; a plurality of second gate meansconnecting said signal generator means with the mixer units of saidsecond set, respectively; and signal processing means having input andoutput terminals connected with the directional filters of said firstand second sets, respectively, for controlling the operation of saidswitch and of said first and second gating means as a function of theinherent characteristics of signals received by said antenna means andfor returning to the directional filter means of said second set amodified facsimile signal.
 1. Apparatus for processing radar signals andthe like, comprising wideband signal receiving and transmitting antennameans; circulator means having a first terminal connected with saidantenna means, said circulator means including also second and thirdterminals; a first tuned microwave mixer set including a firstdireCtional filter, a plurality of first directional filter mixer unitseach tuned to a different discrete frequency band, and first manifoldmeans connecting said first mixer units with said first directionalfilter; a second tuned microwave mixer set including a seconddirectional filter, a plurality of second directional filter mixer unitscorresponding in number with said first mixer units and being tuned tothe corresponding frequency bands thereof, respectively, and secondmanifold means connecting said second mixer units with said seconddirectional filter; first common conductor means connecting the mixerunits of the first set with the second terminal of said circulatormeans, said first conductor means containing a series-connected switch;second common conductor means connecting the mixer units of the secondset with the third terminal of said circulator means; local oscillatorsignal generator means; first gate means connecting said signalgenerator means with all of the mixer units of said first set; aplurality of second gate means connecting said signal generator meanswith the mixer units of said second set, respectively; and signalprocessing means having input and output terminals connected with thedirectional filters of said first and second sets, respectively, forcontrolling the operation of said switch and of said first and secondgating means as a function of the inherent characteristics of signalsreceived by said antenna means and for returning to the directionalfilter means of said second set a modified facsimile signal. 2.Apparatus for processing and repeating radar signals and the like,comprising wideband signal receiving and transmitting antenna means;first and second circulator means each having a first terminal connectedwith said antenna means, and second and third terminals; first, second,third and fourth microwave mixer sets each including a directionalfilter, a plurality of directional filter mixer units each tuned to adifferent discrete frequency band, and manifold means connecting saidfilter mixer units with said directional filter, the mixer units of saidfirst and second sets being of the same number and having correspondingfrequency bands, respectively, the mixer units of said third and fourthsets being of the same number and having corresponding frequency bands,respectively; first common conductor means including a first switchconnecting the mixer units of the first set with the second terminal ofsaid first circulator means; second common conductor means connectingthe mixer units of the second set with the third terminal of said firstcirculator means; third conductor means including a second switchconnecting the mixer units of said third mixer set with the secondterminal of the second circulator means; fourth conductor meansconnecting the mixer units of said fourth mixer set with the thirdterminal of the second circulator means; signal processing and modifyingmeans having input and output terminals; first diplexer means connectingthe directional filters of said first and third mixer sets with theinput terminal of said signal processing and modifying means; seconddiplexer means connecting the output terminal of said signal processingand modifying means with the directional filters of said second andfourth mixer sets; local oscillator signal generator means; first gatemeans connecting said signal generator means with each of the mixerunits of said first and third mixer sets; and a plurality of second gatemeans connecting said signal generator means with the mixer units ofsaid second and fourth mixer sets, respectively; said signal processingand modifying means being operable in accordance with the inherentcharacteristic of the signal received by said antenna means to controlthe operation of said first and second gate means and said first andsecond switches.
 3. An electronic countermeasure syStem for processingthe aircraft-seeking signals generated by a hostile radar installationand for repeating to said radar installation false target echo signals,comprising wideband antenna means operable alternately to receive afirst radar signal and to transmit a processed second radar signal;microwave front end means connected with said antenna means andincluding first tuned mixer means for placing said first signal within agiven first frequency band; second mixing means for modifying the outputsignal of said front end means to produce a signal characteristic of,and having a lower frequency than, said first radar signal; delay meansfor delaying said low frequency signal, said delay means including avariable delay device; doppler correcting means controlling theoperation of said variable delay device to effect a doppler frequencyshift of said low frequency signal corresponding to a desired repeatedecho range rate; means including third mixer means for placing thedelayed and doppler corrected signal in said first frequency band; meansincluding said first tuned mixer means for converting the delayed anddoppler corrected signal in said first frequency band to the originalfrequency of said first radar signal and thereby produce said secondradar signal; means including said antenna for transmitting said secondradar signal toward said hostile radar installation; and computer meansresponsive to the low frequency signal produced by said second mixingmeans for controlling the operation of said first mixing means.